The invention relates to a mold for producing a plurality of moldings, in particular by injection molding, and a method using such a mold.
Injection molding is a very modern, economical method of producing moldings and is particularly well suited to automated mass production. Injection molding consists in heating a heat-deformable casting compound until it becomes liquid, and injecting it under pressure into closed, multi-part hollow molds, which are usually made from steel and cooled by water, where it cools and solidifies.
Polystyrene, polyamides, polyurethanes, cellulose ether and ester, polyethylene, polymethacrylic acid esters, and other heat-deformable materials, thermo-setting plastics which set in the mold or vulcanized elastomers of rubber or silicon rubber, as well as foam plastics, may be used as casting compounds. Wax-type or gel-type materials may also be used, in which case they will generally not have to be heated to such a high degree in order to reach the viscosity needed for the injection molding process.
A standard injection mold has passages extending from one or more injection points and leading to the cavities, which correspond to the structure of the moldings. An injection molding process of this type generally produces moldings joined by webs in a single molded workpiece. The moldings have to be separated from these webs by an appropriate finishing process, which requires at least one additional work step, on the one hand, and leaves behind waste material in the form of the connecting webs, on the other hand. Moreover, the number of moldings which can be produced in one mold is limited.